The present disclosure relates to a fixing device configured to fix a toner image onto a recording medium and an image forming apparatus including the fixing device.
Conventionally, an electrographic image forming apparatus, such as a copying machine or a printer, includes a fixing device configured to fix a toner image onto a recording medium, such as a sheet.
For example, there is a fixing device including a heating body, a pressuring body configured to come into pressure contact with the heating body so as to form a fixing nip, a heat source configured to heat the heating body and a detecting mechanism configured to be not in contact with the heating body.
There is a case that the above-mentioned detecting mechanism includes an infrared detecting element, such as a thermopile. In such a case, the infrared detecting element detects infrared rays radiated from an outer circumferential face of the heating body, and a temperature of the heating body is calculated on a basis of a detecting value thereof or the like.
In the fixing device with above-mentioned configuration, temperature distribution of the heat source is normally not uniform, so that temperature distribution of the heating body heated by the heat source is not uniform, either.
Accordingly, there is fear that detecting accuracy of the infrared detecting element is deteriorated, because a detecting value of the infrared detecting element in a case where the infrared detecting element detects infrared rays radiated from the hottest part in the outer circumferential face of the heating body is greatly different from a detecting value of the infrared detecting element in another case where the infrared detecting element detects infrared rays radiated from the coldest part in the outer circumferential face of the heating body.
Further, in the fixing device with above-mentioned configuration, there is fear that it becomes difficult to dispose the detecting mechanism in a case where the detecting mechanism is greatly protruded toward an outer diameter side of the heating body.